This invention relates generally to prevention of corrosion in well equipment, and more particularly concerns providing well pipe, casing and tubing with corrosion resistant liners which also protect made-up pipe joints.
Oil and gas well pipe, tubing and casing normally consist of relatively low cost, low carbon steel susceptible to hydrogen embrittlement, hydrogen sulfide induced corrosion, and chloride stress corrosion and cracking. While efforts have in the past been made to overcome such problems, they have not met with wide acceptance. For example, while the entire pipe, tubing or casing string may be formed from stainless steel, this is a far too costly solution. Also, while stainless steel liners have been proposed, it is found that hydrogen diffusing into the clearances between the liner and pipe bore causes problems such as hydrogen embrittlement, and deformation of the liner when the hydrogen expands. Further, lining of pipe joints was difficult to achieve and generally unsatisfactory, and plastic linings are subject to local damage such as gouging caused by travel of well tools in the pipe, tubing or casing.